Automotive News reported on Tuesday that federal regulators have launched a probe to investigate a possible fuel tank issue with 1993 to 2004 Jeep Grand Cherokees. The National Highway Traffic Safety Administration is attempting to determine if more than a dozen post-crash fires involving the vehicles are the result of faulty placement of the SUV’s fuel cell. Any problem has the potential to impact more than three million cars currently on the road.

Preliminary information released on Tuesday by the NHTSA suggested that at least 13 deaths in 10 separate crashes were “most likely associated with the alleged defect” in the Grand Cherokees. However, the NHTSA stopped short of blaming the fuel cell’s placement for the fires, stating that the accidents and fires did not necessarily “establish a defect trend” and that a review of early warning data did not find the subject vehicles to be over-represented for post-crash fires.”

The nonprofit Center for Auto Safety petitioned the NHTSA to investigate the fuel tanks in the Grand Cherokee, which they say are improperly positioned to absorb an impact and are known to tear off during crashes. Jeep’s parent company Chrysler Group said it is cooperating with the NHTSA investigation but remained confident that “that a study which considered all factors in all collisions — including rear collisions with fire — would show that the 1993-2004 Jeep Grand Cherokees perform as well as or better than other vehicles in their class.”